Pope Callixtus II or Callistus II, born Guy of Burgundy, reigned from 1 February 1119 to his death in 1124. His pontificate was shaped by the Investiture Controversy, which he was able to settle through the Concordat of Worms in 1122.

Calixtus II devoted his last few years to re-establishing papal control over the Campagna and establishing the primacy of his See of Vienne over the See of Arles, an ancient conflict. He rebuilt the church of Santa Maria in Cosmedin in Rome.